1. Field of the Invention
This invention relates to a cam apparatus for converting continuous rotational motions at a constant speed transmitted from driving sources such as a motor to the input shaft into rotational motions of the output shaft such as intermittent indexing and swing through the cam mechanism, and a pick and place apparatus in which the former is used.
2. Description of the Related Art
So far various types of cam apparatus have been proposed for converting continuous rotational motions at a constant speed transmitted from the driving source such as a motor to the input shaft into rotational motions of a specific pattern such as intermittent indexing through the cam mechanism. Among them, the Japanese Patent Application Laid Open No. 1997-297145 and others disclose cam apparatuses capable of converting the continuous rotational motion at a constant speed of an input shaft and outputting different rotational motions on two output shafts provided on the same shaft.
A sectional side elevation of this cam apparatus is shown in FIG. 12A and a sectional plan view is shown in FIG. 12B.
As illustrated in these plans, an input shaft 117 is rotatably supported on a housing 112 of this cam apparatus 111, and this input shaft 117 continuously rotates at a constant speed being driven by a driving source not shown. On this input shaft 117, a globoidal cam 113 for driving continuous rotation (referred to hereinafter as xe2x80x9ccam for driving continuous rotationxe2x80x9d) and a globoidal cam 115 for driving oscillating rotation (referred to hereinafter as xe2x80x9ccam for driving oscillating rotationxe2x80x9d) are provided jointly in the axial direction. Then, the cam for driving continuous rotation 113 is engaged with a turret 119, causes an output shaft for continuous rotation 121 above to rotate continuously, and further the cam for driving oscillating rotation 115 is engaged with a turret 123 and causes the output shaft for oscillating rotation 125 above thereof to rotate oscillating.
On the outside of this output shaft for oscillating rotation 125, a rotating table 127 is provided on the same shaft through a bearing. On this rotating table 127, an input gear 127a is fixed coaxially. This input gear 127a is engaged with an output gear 121a fixed coaxially on the output shaft for continuous rotation 121, and the continuous rotation of the output shaft for continuous rotation 121 is transmitted to the rotating table 127 (this is also considered as an output shaft, and shall be referred to hereinafter as xe2x80x9coutput shaft 127xe2x80x9d).
By such a configuration, the two output shafts 125 and 127 provided on the same shaft are given the task of performing mutually different rotational motions (oscillating rotational motion and continuous rotational motion for the cam apparatus 111). Further, on this cam apparatus 111, by adequately setting the cam curve of the cam for driving continuous rotation 113 and the cam for driving oscillating rotation 115, the continuous rotational motion at a constant speed of the input shaft can be converted and two output shafts aligned on the same shaft can be given the tasks of performing desired rotational motions.
On the cam apparatus 111, however, the rotational motions of the two output shafts 125 and 127 are mutually independent, and these rotational motions cannot be composed into one motion and outputted. Therefore, when the output shaft is caused to perform a compound rotational motion such that the other output shaft is relatively rotated on the basis of the rotational motion, the cam curve becomes so complex that the work of designing the same becomes extremely difficult, requires a high designing capacity and the designing takes a long period of time.
This invention was made in view of these prior issues and its object is to provide a cam apparatus capable of converting the continuous rotational motion at a constant speed of the input shaft into a compound rotational motion obtained by putting two rotational motions together to drive the output shaft therewith, by means of the cam mechanism having a simple cam curve, as well as a pick and place apparatus using the cam apparatus.
Another object of this invention is to provide a cam apparatus including an input shaft rotatably supported on a housing to be rotated continuously at a constant speed, a first output shaft rotatably supported on the housing and to which rotational motion at an inconstant speed of a specific pattern resulting from the conversion of the continuous rotational motion at a constant speed of the input shaft is transmitted through a rotational motion converting cam mechanism, a slider member provided coaxially to the first output shaft and with freedom of relative displacement along the axial direction through a relative rotation regulating cam mechanism while its relative rotation with the first output shaft is regulated, and to which a reciprocal rectilinear motion in the axial direction of the first output shaft resulting from the conversion of the continuous rotational motion at a constant speed of the input shaft is transmitted through a cam link mechanism, a second output shaft provided coaxially to the first output shaft and rotatably while its movement in the axial direction is regulated, and a motion converting cam mechanism engaged with and between the second output shaft and the slider member, which converts the reciprocal rectilinear motion displacement of the slider member into the oscillating rotational motion displacement of the second output shaft to transmit the same thereto, and transmits the rotational motion at an inconstant speed of the slider member to the second output shaft, wherein the oscillating rotational motion of the slider member and the rotational motion at an inconstant speed of a specific pattern of the first output shaft are compounded and are transmitted to the second output shaft.
Another object of this invention is to provide a pick and place apparatus comprising a cam apparatus including: an input shaft rotatably supported on the housing and continuously driven to rotate at a constant speed, a first output shaft rotatably supported on the housing and to which rotational motion at an inconstant speed of a specific pattern resulting from the conversion of continuous rotational motion at a constant speed of the input shaft is transmitted through a rotational motion converting cam mechanism, a slider member provided coaxially to the first output shaft and with freedom of relative displacement along the axial direction through a relative rotation regulating cam mechanism while its relative rotation with the first output shaft is regulated, and to which a reciprocal rectilinear motion in the axial direction of the first output shaft resulting from the conversion of the continuous rotational motion at a constant speed of the input shaft is transmitted through a cam link mechanism, a second output shaft provided coaxially to the first output shaft and rotatably while its movement in the axial direction is regulated, a motion converting cam mechanism engaged with and between the second output shaft and the slider member, which converts the reciprocal rectilinear motion displacement of the slider member into the oscillating rotational motion displacement of the second output shaft to transmit the same thereto, and transmits the rotational motion at an inconstant speed of the slider member to the second output shaft, in which the oscillating rotational motion of the slider member and the rotational motion at an inconstant speed of a specific pattern of the first output shaft are compounded and are transmitted to the second output shaft; an arm member fixed on the first output shaft and telescopic in the radial direction; and a telescopic driving means that converts the relative rotation generated between the first output shaft and the second output shaft into an expansion or contraction motion of the arm member and transmits as such; wherein the rotational motion at an inconstant speed of the specific pattern of the first output shaft is an intermittent indexing rotational motion, the reciprocal rectilinear motion of the slider member is made while the intermittent indexing rotational motion is stationary, and during the stationary period the arm member expands or contracts at the indexing position.
Still another object of this invention is to provide a pick and place apparatus comprising a cam apparatus including: an input shaft rotatably supported on the housing and continuously driven to rotate at a constant speed, a first output shaft rotatably supported on the housing and to which rotational motion at an inconstant speed of a specific pattern resulting from the conversion of continuous rotational motion at a constant speed of the input shaft is transmitted through a rotational motion converting cam mechanism, a slider member provided coaxially to the first output shaft and capable of relative displacement along the axial direction through a relative rotation regulating cam mechanism while its relative rotation with the first output shaft is regulated, and to which a reciprocal rectilinear motion in the axial direction of the first output shaft resulting from the conversion of the continuous rotational motion at a constant speed of the input shaft is transmitted through a cam link mechanism, a second output shaft provided coaxially to the first output shaft and rotatably while its movement in the axial direction is regulated, a motion converting cam mechanism engaged with and between the second output shaft and the slider member, which converts the reciprocal rectilinear motion displacement of the slider member into the oscillating rotational motion displacement of the second output shaft to transmit the same thereto, and transmits the rotational motion at an inconstant speed of the slider member to the second output shaft, in which the oscillating rotational motion of the slider member and the rotational motion at an inconstant speed of a specific pattern of the first output shaft are compounded and are transmitted to the second output shaft; a snatching means consisting of a pair of snatching arms of which an end is pivotally supported on a base member fixed on the first output shaft; a closing driving means that converts relative rotations generated between the first output shaft and the second output shaft into the unfolding and folding motion of the snatching means and transmits the same; wherein the rotational motion at an inconstant speed of the specific pattern of the first output shaft is an intermittent indexing rotational motion, the reciprocal rectilinear motion of the slider member is made while the intermittent indexing rotational motion is stationary, and during the stationary period the snatching means unfolds and folds at the indexing position.